A form with a long vowel, séin, occurs only in bardic verse
and is usually introduced for the sake of the rhyme:
iaid-séin,
DDána 54.15
(: chéill).
ainnséin,
TD 21.26
(: féin). Without
rhyme:
díbh-séin,
DDána 96.25
.
ei-séin,
80.21
.